1. Field of the Invention
The invention relates to a system for displaying images including a display panel, and more particularly to a touch display panel with an in-cell capacitive induction touch structure.
2. Description of the Related Art
In general, induction methods of in-cell touch display panels comprise an optical induction or an electrostatic induction method. The optical induction touch panel utilizes photo sensors at the pixels to respond to ambient lights, such that the functions of touch panels can be achieved. However, optical induction is easily affected by the brightness of ambient lights and limited by the area of a pixel. When the resolution of an optical induction touch display panel is high and the area of a pixel is small, signals sensed by optical induction are reduced. Additionally, aperture ratio of the optical induction touch display panel decreases due to the photo sensors at the pixels. Thus, problems exist for the optical induction touch display panels.
Another type of touch panel is an in-cell electrostatic induction touch panel, which utilizes capacitance produced by touching of the touch panel to achieve the functions of touch panels. Referring to FIG. 1, a plane view of a conventional electrostatic induction touch panel 100 is shown. The conventional electrostatic induction touch panel 100 has a plurality of rhombus electrically conductive structures 12 and 18. The rhombus electrically conductive structures 12 are arranged in a column, which are connected by an X-axis electrode 10 and coupled to an X-axis circuit 14. The rhombus electrically conductive structures 18 arranged in a row are connected by a Y-axis electrode 16 and coupled to a Y-axis circuit 20. The rhombus electrically conductive structures 12 and the X-axis electrode 10 are disposed in the same conductive layer. The rhombus electrically conductive structures 18 and the Y-axis electrode 16 are disposed in a conductive layer other than the rhombus electrically conductive structures 12 and the X-axis electrode 10. The materials of the conductive layers may be indium tin oxide (ITO). Therefore, the conventional electrostatic induction touch panel 100 needs two ITO conductive layers therein.
Referring to FIG. 2, a cross section of an upper substrate 102 of the conventional electrostatic induction touch panel 100 along the line 2-2′ of FIG. 1 is shown. The upper substrate 102 has a capacitor structure required by the electrostatic induction touch panel therein. First, the X-axis electrode 10 and the rhombus electrically conductive structures 12 are formed on a glass substrate 22, and the X-axis electrode 10 is covered by a dielectric layer 24. Then, the Y-axis electrode 16 and the rhombus electrically conductive structures 18 are formed on the dielectric layer 24. A dielectric layer 26 is formed to cover the Y-axis electrode 16 and the rhombus electrically conductive structures 18. Next, a color filter layer 28 is formed on the dielectric layer 26 and a common electrode layer 30 is formed on the color filter layer 28 and the dielectric layer 26.
The functions of the electrostatic induction touch panels are achieved by detecting capacitance produced by touching of the touch panel, wherein the detected capacitance is provided from the touching areas and the electrically conductive layers of the touch panel. However, the conventional in-cell electrostatic induction touch panel 100 has two conductive layers, for example, the electrodes 10 and 16, such that parasitic capacitances are produced between the two conductive layers 10 and 16 and the common electrode layer 30. Additionally, there is only one dielectric layer 26 disposed between the Y-axis electrode 16 and the common electrode layer 30, such that the parasitic capacitance produced is large. The actually detected capacitance of the touch panel is easily interfered with by the parasitic capacitance, which reduces the sensitivity of the detected signals. Thus, the sensitivity of the detected signals of the conventional in-cell electrostatic induction touch panel 100 is poor.
Therefore, a display panel with an in-cell capacitive induction touch structure that can improve the above mentioned problems is desirable.